This invention relates to a tube pressure filter.
Tube pressure filters are described, for example, in British Patent Specifications Nos. 907,485, 1,240,465 and 1,582,957, in British patent application No. 8301927, and in European Patent Specification No. 0036318. The outer tubular assembly of a tube pressure filter generally comprises a central cylindrical section consisting of, for example, a length of steel tubing of appropriate diameter and wall thickness and two end assemblies, one at each end of the central cylindrical section. Each end assembly includes a collar which is welded to the central cylindrical section.
The weld joining each collar to the central cylindrical section must be impermeable by fluids and must be capable of withstanding pressures of up to 2000 psig (14 MPa.). Such a weld requires the services of a highly skilled welder and is therefore expensive to execute. There is also the risk that the welding operation will distort the ends of the outer tubular assembly to the extent that it is difficult to meet strict tolerances.